1. Field of the Invention
The present invention relates to a rotary-type circuit-component supplying apparatus, a circuit-component feeder, and a circuit-component supplying method, and relates particularly to the art of improving the circuit-component supplying efficiency.
2. Related Art Statement
There is known a rotary-type circuit-component supplying apparatus which includes a circular (i.e., full-circular) table, and a plurality of feeders which are held by the circular table and each of which includes a component-supply portion. When the table is rotated, the component-supply portion of each of the feeders is sequentially positioned at a component-supplying position where the each feeder supplies at least one circuit component from the component-supply portion thereof. In this rotary-type circuit-component supplying apparatus, each of the feeders stores a plurality of circuit components of a same sort and supplies the components one by one from the component-supply portion thereof, and the circular table is rotatable about an axis line which is substantially vertical and holds the feeders such that the respective component-supply portions of the feeders are arranged along a circle having a center on the axis line. The present apparatus further includes a table-driving device which rotates and stops the circular table to position the component-supply portion of each of the feeders at a predetermined component-supplying position.
Each feeder may be one which includes a main portion which supports a feeding mechanism which feeds a tape carrying circuit components to a component-supply portion thereof, and a reel-holding portion which holds a reel around which the tape is wound. In the known feeder, the component-supply portion thereof is provided by one of opposite end portions thereof in a tape-feeding direction in which the tape is fed by the feeding mechanism, and the reel-holding portion thereof is provided by the other end portion thereof. The main portion and the reel-holding portion are arranged in series in the tape-feeding direction, and are provided in a common plane such that at least a portion of the reel-holding portion overlaps the main portion in a direction perpendicular to the tape-feeding direction and the direction of width of the main portion.
The rotary-type circuit-component supplying apparatus enjoys a more compact construction than a linear-type circuit-component supplying apparatus which includes a plurality of feeders, a movable table which is movable along a straight line and which supports the feeders such that respective component-supply portions of the feeders are arranged along the straight line, and a driving device which moves and stops the table along the straight line to position the component-supply portion of each of the feeders at a component-supplying position where the each feeder supplies at least one circuit component from the component-supply portion thereof. The linear-type apparatus needs, in addition to a space which is occupied by the table, a space in which the table is moved. Thus, the linear-type apparatus needs at least two times as much space as that needed by the rotary-type apparatus. In addition, it can be generally said that when the circular table is rotated, the table generates only the momentum about the axis line of rotation thereof. Therefore, the rotary-type apparatus produces less vibration than the linear-type apparatus. Accordingly, the vibration of the floor on which the rotary-type apparatus is placed is reduced, which leads to prevent operators working on the floor from feeling discomfort and which leads to preventing other apparatuses placed on the same floor, from suffering problems which would otherwise be caused by the vibration, for example, lowered accuracy of positioning of a movable member.
However, the known rotary-type circuit-component supplying apparatus has some problems to be solved for improving its circuit-component supplying efficiency. For example, when the tape carrying the circuit components has been completely consumed on each feeder, the reel of the feeder, or the feeder itself, should be replaced by another reel or feeder. To this end, the operation of the supplying apparatus must be stopped. Accordingly, in recent years, it has been practiced to employ a long tape for reducing the frequency of the replacing or stopping operations and thereby improving the supplying efficiency. However, the longer the tape is, the greater the size of the reel or the reel-holding portion should be. Thus, it is more difficult for each feeder to be mounted on the circular table. As described above, in the known feeder, the component-supply portion thereof is provided by one of opposite end portions of the main portion thereof, and the reel-holding portion thereof is connected to the other end portion of the main portion. The known feeder must be mounted on the circular table, such that the component-supply portion thereof is located along the outer peripheral portion of the table and the reel-holding portion is located on the side of the axis line of rotation of the table. Accordingly, in order to mount, on a circular table, a feeder having a great reel-holding portion which can hold a reel having a great diameter, the circular table should also have a great diameter. In addition, generally, the reel-holding portion has a greater width than that of the main portion. Since the feeders are mounted on the circular table having an annular shape such that the reel-holding portions of the feeders are located along the inner peripheral portion of the annular table, it is easy to provide a sufficient space between each pair of adjacent main portions, whereas it is difficult to provide a sufficient space between each pair of adjacent reel-holding portions. Thus, the maximum number of feeders that can be mounted on the circular table is limited to a small one. Accordingly, the frequency of the reel or feeder replacing operations cannot be reduced and the circuit-component supplying efficiency cannot be improved. An increased number of feeders can be mounted on a circular table having an increased diameter. In the last case, however, the inertial moment of the circular table and the feeders held thereby is increased, and the acceleration and deceleration at which the table is rotated should be lowered for reducing the vibration produced thereby. Eventually, a longer time is needed for positioning each feeder, which lowers the supplying efficiency.